According to the Centers for Disease Control and Prevention, the rates of all of our top 10 killers have fallen or stabilized except for one, suicide. As shown in my video, Antioxidants & Depression, accumulating evidence indicates that free radicals may play important roles in the development of various neuropsychiatric disorders including major depression, a common cause of suicide.

In a study of nearly 300,000 Canadians, for example, greater fruit and vegetable consumption was associated with lower odds of depression, psychological distress, self-reported mood and anxiety disorders and poor perceived mental health. They conclude that since a healthy diet comprised of a high intake of fruits and vegetables is rich in anti-oxidants, it may consequently dampen the detrimental effects of oxidative stress on mental health.

But that study was based on asking how many fruits and veggies people ate. Maybe people were just telling the researchers what they thought they wanted to hear. What if you actually measure the levels of carotenoid phytonutrients in people's bloodstreams? The same relationship is found. Testing nearly 2000 people across the United States, researchers found that a higher total blood carotenoid level was indeed associated with a lower likelihood of elevated depressive symptoms, and there appeared to be a dose-response relationship, meaning the higher the levels, the better people felt.

Lycopene, the red pigment predominantly found in tomatoes (but also present in watermelon, pink grapefruit, guava and papaya) is the most powerful carotenoid antioxidant. In a test tube, it's about 100 times more effective at quenching free radicals than a more familiar antioxidant like vitamin E.

Do people who eat more tomatoes have less depression, then? Apparently so. A study of about a thousand older men and women found that those who ate the most tomato products had only about half the odds of depression. The researchers conclude that a tomato-rich diet may have a beneficial effect on the prevention of depressive symptoms.

Higher consumption of fruits and vegetables has been found to lead to a lower risk of developing depression, but if it's the antioxidants can't we just take an antioxidant pill? No.

Only food sources of antioxidants were protectively associated with depression. Not antioxidants from dietary supplements. Although plant foods and food-derived phytochemicals have been associated with health benefits, antioxidants from dietary supplements appear to be less beneficial and may, in fact, be detrimental to health. This may indicate that the form and delivery of the antioxidants are important. Alternatively, the observed associations may be due not to antioxidants but rather to other dietary factors, such as folate, that also occur in plant-rich diets.

In a study of thousands of middle-aged office workers, eating lots of processed food was found to be a risk factor for at least mild to moderate depression five years later, whereas a whole food pattern was found to be protective. Yes, it could be because of the high content of antioxidants in fruits and vegetables but could also be the folate in greens and beans, as some studies have suggested an increased risk of depression in folks who may not have been eating enough.

Low folate levels in the blood are associated with depression, but since most of the early studies were cross-sectional, meaning a snapshot in time, we didn't know if the low folate led to depression or the depression led to low folate. Maybe when you have the blues you don't want to eat the greens.

But since then a number of cohort studies were published, following people over time. They show that a low dietary intake of folate may indeed be a risk factor for severe depression, as much as a threefold higher risk. Note this is for dietary folate intake, not folic acid supplements; those with higher levels were actually eating healthy foods. If you give people folic acid pills they don't seem to work. This may be because folate is found in dark green leafy vegetables like spinach, whereas folic acid is the oxidized synthetic compound used in food fortification and dietary supplements because it's more shelf-stable. It may have different effects on the body as I previously explored in Can Folic Acid Be Harmful?

These kinds of findings point to the importance of antioxidant food sources rather than dietary supplements. But there was an interesting study giving people high dose vitamin C. In contrast to the placebo group, those given vitamin C experienced a decrease in depression scores and also greater FSI. What is FSI? Frequency of Sexual Intercourse.

Evidently, high dose vitamin C improves mood and intercourse frequency, but only in sexual partners that don't live with one another. In the placebo group, those not living together had sex about once a week, and those living together a little higher, once every five days, with no big change on vitamin C. But for those not living together, on vitamin C? Every other day! The differential effect for non-cohabitants suggests that the mechanism is not a peripheral one, meaning outside the brain, but a central one--some psychological change which motivates the person to venture forth to have intercourse. The mild antidepressant effect they found was unrelated to cohabitation or frequency, so it does not appear that the depression scores improved just because of the improved FSI.

According to the Centers for Disease Control and Prevention, the rates of all of our top 10 killers have fallen or stabilized except for one, suicide. As shown in my video, Antioxidants & Depression, accumulating evidence indicates that free radicals may play important roles in the development of various neuropsychiatric disorders including major depression, a common cause of suicide.

In a study of nearly 300,000 Canadians, for example, greater fruit and vegetable consumption was associated with lower odds of depression, psychological distress, self-reported mood and anxiety disorders and poor perceived mental health. They conclude that since a healthy diet comprised of a high intake of fruits and vegetables is rich in anti-oxidants, it may consequently dampen the detrimental effects of oxidative stress on mental health.

But that study was based on asking how many fruits and veggies people ate. Maybe people were just telling the researchers what they thought they wanted to hear. What if you actually measure the levels of carotenoid phytonutrients in people's bloodstreams? The same relationship is found. Testing nearly 2000 people across the United States, researchers found that a higher total blood carotenoid level was indeed associated with a lower likelihood of elevated depressive symptoms, and there appeared to be a dose-response relationship, meaning the higher the levels, the better people felt.

Lycopene, the red pigment predominantly found in tomatoes (but also present in watermelon, pink grapefruit, guava and papaya) is the most powerful carotenoid antioxidant. In a test tube, it's about 100 times more effective at quenching free radicals than a more familiar antioxidant like vitamin E.

Do people who eat more tomatoes have less depression, then? Apparently so. A study of about a thousand older men and women found that those who ate the most tomato products had only about half the odds of depression. The researchers conclude that a tomato-rich diet may have a beneficial effect on the prevention of depressive symptoms.

Higher consumption of fruits and vegetables has been found to lead to a lower risk of developing depression, but if it's the antioxidants can't we just take an antioxidant pill? No.

Only food sources of antioxidants were protectively associated with depression. Not antioxidants from dietary supplements. Although plant foods and food-derived phytochemicals have been associated with health benefits, antioxidants from dietary supplements appear to be less beneficial and may, in fact, be detrimental to health. This may indicate that the form and delivery of the antioxidants are important. Alternatively, the observed associations may be due not to antioxidants but rather to other dietary factors, such as folate, that also occur in plant-rich diets.

In a study of thousands of middle-aged office workers, eating lots of processed food was found to be a risk factor for at least mild to moderate depression five years later, whereas a whole food pattern was found to be protective. Yes, it could be because of the high content of antioxidants in fruits and vegetables but could also be the folate in greens and beans, as some studies have suggested an increased risk of depression in folks who may not have been eating enough.

Low folate levels in the blood are associated with depression, but since most of the early studies were cross-sectional, meaning a snapshot in time, we didn't know if the low folate led to depression or the depression led to low folate. Maybe when you have the blues you don't want to eat the greens.

But since then a number of cohort studies were published, following people over time. They show that a low dietary intake of folate may indeed be a risk factor for severe depression, as much as a threefold higher risk. Note this is for dietary folate intake, not folic acid supplements; those with higher levels were actually eating healthy foods. If you give people folic acid pills they don't seem to work. This may be because folate is found in dark green leafy vegetables like spinach, whereas folic acid is the oxidized synthetic compound used in food fortification and dietary supplements because it's more shelf-stable. It may have different effects on the body as I previously explored in Can Folic Acid Be Harmful?

These kinds of findings point to the importance of antioxidant food sources rather than dietary supplements. But there was an interesting study giving people high dose vitamin C. In contrast to the placebo group, those given vitamin C experienced a decrease in depression scores and also greater FSI. What is FSI? Frequency of Sexual Intercourse.

Evidently, high dose vitamin C improves mood and intercourse frequency, but only in sexual partners that don't live with one another. In the placebo group, those not living together had sex about once a week, and those living together a little higher, once every five days, with no big change on vitamin C. But for those not living together, on vitamin C? Every other day! The differential effect for non-cohabitants suggests that the mechanism is not a peripheral one, meaning outside the brain, but a central one--some psychological change which motivates the person to venture forth to have intercourse. The mild antidepressant effect they found was unrelated to cohabitation or frequency, so it does not appear that the depression scores improved just because of the improved FSI.

In the prevention of cardiovascular disease, the consumption of fruits and vegetables is crucial. Preventing the oxidation of cholesterol may be one of the mechanisms by which fruits and vegetables reduce the risk of heart attacks and strokes. However, hyperactivity of platelets is also critically important in the pathogenesis of cardiovascular disease, as I've covered before (See Inhibiting Platelet Aggregation with Berries).

In recent years, it has been shown that platelets are not only involved in the arterial clotting process, but also that they play an active role in the inflammatory process of atherosclerosis from childhood. By the end of our teens, atherosclerotic lesions are present in most people living in industrialized societies, and so suppressing the over-activity of platelets may be beneficial not only for heart disease, but for cancer, allergies, and diseases for which inflammation plays a major role.

The antioxidant properties of fruits and veggies are well known. However, their anti-clotting effects on platelets are less known. Preliminary studies have demonstrated the platelet activation suppressing activity of a variety of fruits and vegetables. They suppress platelet activation so well that they can actually mess up platelet function tests. And, the effects are so long-lasting that fasting the morning of your blood test may not be sufficient.

Out of 16 different fruits tested, tomatoes came out number one. The anti-platelet activation components in tomatoes are water soluble, so we don't have to eat them with fat; heat stable, meaning we can cook tomatoes without losing the benefits; and concentrated in the yellow fluid around the seeds. This is why tomato pomace beat out tomato juice, sauce, or ketchup. Pomace is basically the seeds and the peel, which the industry throws away, and it may be the healthiest part. And the more tomato seeds the better. But this study was measuring platelet activation in a petri dish. Grapefruit came in number two here, and grapefruit juice at least didn't appear to help when people actually drank it. Would drinking tomato juice actually help?

Platelets of patients with diabetes are characterized by intensified activation, so 20 diabetics were asked to drink a daily cup of tomato juice for three weeks or a tomato-flavored placebo beverage, and there was a significant drop in platelet activation.

A study done by the Rowett Research Institute, highlighted in my video, Inhibiting Platelet Activation with Tomato Seeds, found this works in healthy people as well. Within three hours of consumption, two tomatoes lowered platelet activation, and six tomatoes worked even better. Also, the effects were more wide-ranging than those of aspirin in that the tomatoes targeted multiple pathways of platelet activation.

About one in four people are aspirin resistant, meaning aspirin doesn't work to calm down their platelets, whereas only 3% of study subjects were found to be tomato resistant.

This finding indicates an advantage of the tomato extract's broad antiplatelet activity profile over single-target drugs such as aspirin. Also, when researchers stuck tubes into people while they were eating tomatoes, they found no changes in blood clotting times, implying that supplementation with tomatoes should not result in a prolonged bleeding times, so one might get the best of both worlds: less platelet activation without the bleeding risk. But if tomatoes don't thin our blood, do they work?

Researchers out of North Carolina State University report that, "consumption of tomato products has been found to be protectively correlated with a lower incidence of acute coronary events, less development of early atherosclerosis, and lower mortality from heart disease."

If you don't like tomatoes, kiwifruit recently beat them out in a test tube study of platelet activation. Strawberries may help too, but we have data showing kiwis may actually work in people, and two kiwis appeared to work just as well as three kiwis. It appears to work for green-on-the-inside kiwifruit; and for yellow-on-the-inside kiwifruit. In this case, though, one a day seemed to help whereas two-a-day did not, which seems a little strange. And there haven't been any studies to see if kiwifruit eaters actually have fewer strokes and heart attacks, so the best evidence for a dietary intervention to decrease platelet activation currently rests with tomatoes.

If someone eats half of a grapefruit three times a day before each meal for a couple months, they may lose about two pounds -- but that's no more than if they ate three apples or pears a day. In one study, the grapefruit eaters not only saw their weight go down, but their waist got slimmer, and their body fat melted away. If, however, we repeat the experiment and instead ask people to drink a half cup of water before each meal, we get the same result. So this belief that grapefruit has some special fat-burning quality appears to be just a long-held myth.

The researchers reported that grapefruit consumers had a drop in weight, a significant drop in cholesterol, and a significant drop in blood pressure. They concluded that consumption of grapefruit daily for six weeks does not significantly decrease body weight, cholesterol, or blood pressure, though. That made me do a little double take, but again, it's because the grapefruit didn't do any better than placebo.

Other studies have found a legitimate cholesterol-lowering benefit of grapefruit, and even a little dip in triglycerides, especially eating red as opposed to white . For example, one study showed a decrease in cholesterol, but only from one life-threatening cholesterol level to another life-threatening cholesterol level. To prevent heart disease, we really have to get down to a total cholesterol of around 150, which is the average cholesterol of those eating diets composed exclusively of plant foods, not just grapefruits (See, for example, One in a Thousand: Ending the Heart Disease Epidemic).

Even though grapefruits alone don't do much, the researchers suggest that people might be more likely to stick with them than cholesterol lowering drugs, noting that most people with heart disease stop taking their statin drugs within a couple years because of the adverse side effects (see Statin Muscle Toxicity). While grapefruits alone don't have any side effects, ironically, combining grapefruits and drugs can make drug side effects even worse.

If we eat lots of fruits and vegetables, we hopefully won't need a lot of drugs (Say No to Drugs by Saying Yes to More Plants), but certain phytochemicals in plants can affect the metabolism of drugs in the body. Grapefruit is the poster child, described as a "pharmacologist's nightmare." Natural phytochemicals in grapefruit suppress the enzymes that help clear more than half of commonly prescribed drugs, and less drug clearance means higher drug levels in the body. This may actually be good if we want a better caffeine buzz from our morning coffee, or our doctors want to help us save thousands of dollars by boosting the effects of expensive drugs instead of just peeing them away.

But higher drug levels may mean higher risk of side effects. Women taking the Pill are normally at a higher risk of blood clots, but even more so, perhaps, if they have been consuming grapefruit. Taking the Pill with grapefruit juice may increase blood drug concentrations by 137 percent.

If suppressing our drug clearance enzymes with grapefruit juice elevates levels of ingested estrogen, what might it be doing to our own estrogen levels? A study associating grapefruit consumption with breast cancer freaked out the medical community, but subsequent studies on even larger groups of women found no evidence of a link. The Harvard Nurses' Study even found a decreased risk of the scariest breast cancer type, so it doesn't look like we have to worry about grapefruit affecting our natural chemistry.

For those prescribed unnatural chemistries, it may be a good idea to discontinue grapefruit consumption for 72 hours before use of a drug that may interact with it. If you don't want to give up your grapefruit, you can ask your doctor about switching from a grapefruit-affected drug like Lipitor to one of the citrus-proof alternatives (the replacement drug chart can be seen in my video, Tell Your Doctor If You Eat Grapefruit).

The lactic acid that makes yogurt tangy is the same lactic acid that builds up in our muscles when we exercise strenuously. Instead of bacteria fermenting the sugar in milk to make energy for themselves, our muscles ferment sugar in our diet to produce energy to contract. If, like when we’re sprinting, lactic acid builds up in our muscles faster than it can be removed we can end up with a burning sensation in our muscles, forcing us to stop.

Now if we train, we can increase the number of blood vessels in our muscles and clear out the lactate faster. For example, when researchers took some overweight sedentary women and started them on an aerobic training program of running and walking, at the end of three months, their lactate levels during exercise dropped 17%. But those on the same program who drank two cups of orange juice a day dropped their levels 27%. They did the same exercise program, but the citrus group experienced a significant decrease in blood lactate concentration, indicating an improvement in physical performance with less muscle fatigue.

I don’t recommend drinking juice, though, because we’re losing all that wonderful fiber that slows the rate of fruit sugar absorption into our system. In my video, Reducing Muscle Fatigue with Citrus, we can see the blood sugar spike one might expect after drinking Coca-Cola. Compare that to the spike we see with orange juice? No difference. However, if we eat the same quantity of sugar in the form of orange slices we experience a significantly smaller spike in blood sugar.

So the whole fruit is nearly always better than fruit juice. Now this is not to say OJ isn’t better than coke. OJ has those citrus phytonutrients like hesperidin, which may be why the women’s triglycerides didn’t go up even though they were drinking two cups of fruit juice every day. Hesperidin may actually help lower our digestion of fats, but once we get up to three cups a day, we really can start bumping our triglycerides.

The burning sensation during strenuous exercise may be related to the build-up of lactic acid in our muscles, but that’s different than the delayed onset muscle soreness that occurs in the days following a bout of extreme physical activity. That’s thought to be due to inflammation caused by muscle cell damage, little micro-tears in the muscle. If it’s an inflammatory reaction then might anti-inflammatory phytonutrients help? Find out in my video Reducing Muscle Soreness with Berries.

In 1936, Albert Szent-Györgyi, who won the Nobel Prize for discovering vitamin C, described a vitamin “P,” which we now know encompasses a class of thousands of phytonutrients called flavonoids. Some, like quercitin, are widespread in plant-based foods. We can tell something is widespread in the plant kingdom when one can even find it in iceberg lettuce!

Others, however, are only found in specific plant families. For example, hesperidin is found primarily in citrus fruits. This may be one of the reasons that, out of all the different types of fruit that have been looked at, citrus may cut our risk of stroke the most.

The citrus phytonutrient hesperidin increases blood flow. Using a machine called a Doppler fluximeter (sounds like something from Back to the Future) one can measure blood flow through the skin using a laser beam. When researchers give people the amount of hesperidin found in two cups of orange juice, blood flow goes up. It works even better when they gave them the orange juice itself, so there’s other beneficial stuff besides just the hesperidin in citrus.

For example, if we measure the changes in genetic expression, orange juice consumption induces changes in the expression of 3000 of our genes, whereas hesperidin alone only modulated the expression of about 2000. Still, the fact that nearly 2000 stretches of our DNA expressed differently because we consumed just one of the thousands of phytonutrients in plants is pretty mind-blowing.

These changes in blood flow are not just in theory. Researchers took volunteers with cold sensitivity (cold hands and feet), put them in an air-conditioned room and measured the temperature of their fingertips after drinking a placebo drink (like orange Kool-Aid) versus drinks with two doses of actual citrus phytonutrients. In the Kool-Aid group, their fingers got colder and colder, dropping nearly nine degrees Fahrenheit. The fingers of those consuming low or high doses of citrus didn’t get nearly as cold because their blood flow remained steady. In my video, Keeping Your Hands Warm with Citrus, we can see the laser test of the subject's blood flow. When we’re exposed to cold temperatures our body starts to clamp off peripheral blood flow to keep our core warm, but if we eat a bunch of oranges before we go skiing our risk of frostbite may go down since we’re keeping up our blood flow to our fingers and toes.

They even took these poor women and plunged their hands into some chilly water, and their finger temperature rebounded faster towards normal in the citrus group, demonstrating that citrus phytonutrients not only keep our extremities warmer but may also warm us back up faster.

But don't forget, don't brush your teeth immediately after consuming citrus. We have to make sure to rinse our mouth with water and wait 30 minutes before brushing to protect our tooth enamel (see Plant-Based Diets: Dental Health).

Because different families of fruits and vegetables can have entirely different phytonutrient profiles, variety is important. See, for example: